@conference {60932,
	title = {Strategically reducing time on pasture: Dairy cow intake, production, welfare, and excretory behaviour},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {69},
	year = {2009},
	month = {Jun},
	pages = {15-19},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {In wet spring conditions, cows are often stood off pasture reducing their pasture intake. However, studies indicate that despite reduced grazing access, pasture intake and milk production can be maintained. This study restricted daily grazing access to eight hours in early lactation to determine the effect on pasture intake, milk production, and urination distribution. Forty-eight Holstein-Friesian cows were allocated to three duplicated treatments. Cows had access to pasture for either four hours after each milking (2x4), eight hours between milkings (1x8), or for 24 hours, excluding milking times (Control). When not grazing, the 2x4 and 1x8 treatments were stood off on a bark pad. The 1x8 cows ate less pasture (10.9 kgDM/cow/d; P <0.05) than the Control (13.6 kgDM/cow/d), but the 2x4 intake (13.0 kgDM/cow/d; P = 0.46) was not different to the Control. The 1x8 and 2x4 cows produced less milk (20.2 and 21.5 kg milk/cow/d respectively; P <0.05), relative to the Control (23.3 kg milk/cow/d). Urinations on pasture and races were reduced (P <0.05) from 90\% (Control) to 62\% (1x8) and 65\% (2x4) of total urinations. Eight-hours grazing per day should be offered as two four-hour periods to maintain cow pasture intakes, although milk yields are reduced. Corresponding changes in urination distribution may have environmental benefits. },
	issn = {1176-5283},
	author = {McLeod KLM and Clark CEF and Glassey CB and Gregorini P and Costall DA and Betteridge K and Jago JG}
}
@conference {41572,
	title = {Comparing feed allowances to inferred energy intake using data from a dairy grazing farm trial},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {225-230},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The main objective of this research was to investigate whether calculating intake of dairy cows using equations to predict energy requirements provides a good alternative to conventional ways of estimating intake. The method was applied to data from the Dexcel Holstein-Friesian strain trial over three seasons. Feed intake per cow was calculated as the sum of the energy requirements for maintenance, milk production, pregnancy, growth and body tissue mobilisation using measured yields of milk, fat, protein and lactose, live weight and body condition score of cows and calf live weights. In order to compare the estimates of feed intake to the amount of feed offered, linear regressions of calculated (ME) intake (grouped by farmlet) on the amount ME offered per farmlet were performed by season. The relationship between ME intake and ME offered was weak in the first year, with a limited response to increasing the amount of feed offered. This was because all the cows were two-year-olds with lower live weights and milk yields and consequently lower feed intakes. In the subsequent two years of the trial, the relationship between ME intake calculated using the energy equations were 67\% and 72\%. The modern strains of dairy cows responded well to higher levels of feed offered, while the 1970s strain of New Zealand dairy cows failed to increase intake when offered diets of higher total ME. Our results show that energy prediction equations offer a viable and cheap alternative of estimating ME intake of lactating dairy cows.
KEYWORDS: dairy cows; energy intake; strain comparison; efficiency. },
	issn = {1176-5283},
	author = {Pryce JE and Harris BL and Montgomerie WA and Jackson R and MacDonald KA and Glassey CB and Thorrold BS and Holmes CW}
}
@conference {41539,
	title = {Economic comparison of Holstein-Friesian strains},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {68-73},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The objective of this research was to identify major determinants of net profit per cow. Data were from the Dexcel strain trial over three seasons, in which Holstein-Friesian cows were managed in groups of 12 to 20 cows in eleven farmlets. Milk returns were calculated from lactation yields of milk, fat and protein. Net profit per cow was calculated as the net return from milk sales plus sales of calves minus feed, fertility, health, shed and working expense costs. Annualised present values were derived using asset replacement theory and discounting to account for different numbers of years of data according to the year in which an animal entered the herd. Net replacement costs and average replacement returns were included where animals were replaced before the end of the trial. Partition analysis was used to identify indicators of cow profitability. Partition analysis recursively sub-divides data creating a tree of partitions. Each split is chosen to maximise the difference in profitability between branches of the split. Variables on which data could be partitioned included breeding values, Breeding Worth and traits measured in first parity. The key determinants of profitability were lactation yield of protein and fat, percentage of fat and Breeding Worth. When these variables were fitted to a multiple regression model where the response was annualised present value, the adjusted R2 was 52\%.
KEYWORDS: asset replacement model; economics; dairy cattle. },
	issn = {1176-5283},
	author = {Pryce JE and Harris BL and Glassey CB and Montgomerie WA and Jackson R and MacDonald KA and Thorrold BS and Holmes CW}
}
@conference {41834,
	title = {The effect of genotype on milk composition, milk value and dairy farm profitability},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {276-282},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {This study was conducted to determine the effect of genotype on milk composition, milk value and economic farm surplus (EFS). The trial included two high breeding worth ($BW) strains of either North American (OS90) or New Zealand (NZ) (NZ90) genetics, and one low $BW strain of NZ genetics (NZ70). Each strain was farmed under systems designed to provide total feed allowances of 4.5 to 7.0 t DM/cow/year. For two years (2001/2002 \& 2002/2003) monthly average milk yield and composition were determined for each of the 11 herds. A simulation model was used to calculate milk value using three product mixes. Using either the simulated values or actual values (paid by Fonterra 2002/2003) for milk and its components, milk value ($/litre and $/kg milksolids (MS)) and an EFS for each herd was determined. The OS90 strain produced milk with lower concentrations of fat and protein and higher protein:fat ratio than NZ70 or NZ90 strains. The effect of strain on milk price was unaffected by product mix. Milk value differed between strains irrespective of method of determination. Milk value expressed as $/kg MS was lowest for the NZ70 and highest (P < 0.001) for the OS90 strain. When expressed as $/litre milk value was highest (P < 0.001) for the NZ90 strain. Milk value expressed as $/kg MS was positively associated with protein:fat ratio whereas milk value expressed as $/litre was positively associated with MS concentration. Average EFS was greater for the NZ90 than the NZ70 strain and was least for the OS90 strain. The factors associated with EFS were MS production; milk value and milk composition had minimal impact. New Zealand{\textquoteright}s dairy cattle breeding programme has produced a strain of Holstein- Friesian with increased milk fat and protein concentration, an increased protein:fat ratio, and an associated increased milk value and increased EFS. In comparison, the OS90 strain which the current $BW index ranks as high as the NZ90, produced milk with higher value ($/kg MS) but resulted in lower EFS.
Key words: milk price; milk value; milk composition; economic farm surplus. },
	issn = {1176-5283},
	author = {Thomson NA and Turner S-A and Glassey CB and Lopez-Villalobos N}
}
@conference {41534,
	title = {Impact of farm management decision rules on the production and profit of different strains of Holstein-Friesian dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {40-45},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Management decision rules ({\textquoteleft}old{\textquoteright} rules) have been used at the Dexcel No. 2 Dairy Farm to remove subjectivity from the management of farm systems research and have also been promoted to the dairy industry. A trial involving these rules where three strains of Holstein-Friesian (HF) cows were compared has completed its third season. The trial included two high breeding worth (BW) strains of either North American (OS90) or New Zealand (NZ90) genetics, and one low BW strain of NZ genetics (NZ70). Under the {\textquoteleft}old{\textquoteright} rules the OS90 cows had fewer days in milk than the other two strains, mainly because they were dried off earlier due to their lower body condition score (BCS). In the third lactation {\textquoteleft}new{\textquoteright} rules were applied that allowed cows at the higher feed allowances to be dried off later (but at the same BCS) than would have been allowed under the {\textquoteleft}old{\textquoteright} rules. For the herds receiving the higher feed allowances, this change resulted in increased days in milk (NZ90 + 2 days; OS90 + 17 days) more milksolids (MS) per cow (NZ90 +2 kg; OS90 +21 kg), and more feed required (NZ90 + 10 kg; OS90 + 157 kg DM/cow) with all herds reaching target BCS by their next calving. It is calculated that this reduced the difference in economic farm surplus (EFS) per ha between the NZ90 and OS90 from $488 to $219. These results indicate the need to alter management rules to get the best performance from North American HF genetics.
KEYWORDS: Holstein-Friesian; body condition score; drying-off decision rules. },
	issn = {1176-5283},
	author = {MacDonald KA and Thorrold BS and Glassey CB and Holmes CW and Pryce JE}
}
@conference {41554,
	title = {Modelling the effects of zero-inductions on profitability in dairy systems},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {132-136},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {Inductions are an animal welfare issue and regulations aim to achieve < 2\% inductions on a national basis by 2010. There is a need to assess the longer-term impacts of alternative reproduction management strategies on farm economics and their success in solving the problem of poor reproductive performance. Dexcel{\textquoteright}s Whole Farm Model was calibrated against observed data from Lincoln University Dairy Farm where 11\% of the herd was subjected to inductions in the 2002/03 season, but a zero-induction policy has since been adopted. Results from one-year simulations over five different climate years showed a significant decrease in farm profit ($105/ha, P < 0.05) from the benchmark farm with 11\% inductions (following {\textquoteleft}best practice{\textquoteright} guidelines) to a farm where the late-calvers were culled and replaced by bought-in early-calving heifers and where stocking rate was raised moderately (< 10\%) to compensate for the higher proportion of heifers in the herd. Multiple-year simulations reflecting carry-over effects showed that a strategy with a 10-week mating period, annual culling of 25\% of the herd including all empties and replacement with synchronized heifers mated to start calving one week before planned start of calving can match the farm profitability of the {\textquoteleft}Induction{\textquoteright} strategy if implemented consistently for 5-8 years.
Key words: calving spread; modelling; synchrony; mating; replacement. },
	issn = {1176-5283},
	author = {Beukes PC and Thorrold BS and Wastney ME and Glassey CB and Burke CR and Van Bysterveldt AM}
}
@conference {41538,
	title = {The productivity of pasture-based dairy farms in New Zealand with different levels of extra feed input},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {65},
	year = {2005},
	month = {Jan},
	pages = {63-67},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Christchurch},
	abstract = {The objective of this research was to study the physical and financial performance of commercial dairy farms in New Zealand that differed in the amount of extra feed used. Data from Dexcel{\textquoteright}s ProfitWatch corresponding to 626 owner-operated dairy farms between 1998/1999 and 2001/2002 were analysed. The data were classified according to each of the four dairy seasons and the extra feed used per cow. Extra feed comprised supplements imported (hay, pasture silage, maize silage, concentrates and other feeds), winter grazing and maize silage grown on the farm. The statistical analyses were done in SAS and comprised analyses of variance and regression analyses. High feed input farms (H farms, 740-940 kg extra DM /cow/year) had higher stocking rates (2.7-2.8 vs 2.4-2.5 cows/ha), lower comparative stocking rate (83-86 vs 83-92 kg live weight/t DM), and higher milksolids (MS) production per cow (293-341 vs 249-295 kg MS/cow) and per hectare (826-921 vs 616-744 kg/ha) than low feed input farms (L farms, 20 kg DM extra feed/cow/year). The use of nitrogen fertiliser was also higher in the H farms than in L farms (85-116 vs 53-67 kg N/ha/year). There were no significant differences in farm size, herd breeding worth, reproductive characteristics of the herds and estimated pasture consumed per hectare. On average, extra feed was significantly associated with extra cows (0.17 extra cows/ha for 1 t extra DM) and extra milk solids (50 g extra MS/cow for 1 kg extra DM/cow and 96 g extra MS/ha for 1 kg extra DM/ha), but the wide variability is shown by the low values for R2 (0.13 to 0.16 for the three relations above). The H farms produced higher gross farm incomes per hectare (by $0.47 to $0.49/kg extra DM offered) but had higher farm working expenses per hectare (by $0.36 to $0.37/kg extra DM offered), so that Economic Farm Surplus per hectare was not higher for these farms in any year. High management skills and control of costs are necessary for profit to be increased by the use of extra feeds.
KEYWORDS: low-input; high-input; extra feed. },
	issn = {1176-5283},
	author = {Silva-Villacorta D and Holmes CW and Shadbolt NM and Lopez-Villalobos N and Prewer W and Glassey CB and Blackwell M}
}
@conference {40453,
	title = {Milk Production and Production Index Comparisons in Mixed Breed Dairy Herds},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {53},
	year = {1993},
	month = {Jan},
	pages = {47-50},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Liveweight, milk yield and feed intake were measured in two experiments, the first with 30 cows grazing on pasture and the second with 16 cows fed indoors on fresh pasture. Feed intakes by the grazing cows were estimated from faecal outputs, using chronic oxide as the indigestible marker.  The relation between daily metabolisable energy intake (MEI), daily milk energy output, liveweight 0.75 (LW0.75) and daily change in liveweight were examined by multiple regression analysis. Milk energy was significantly related to MEI, and therefore (at a common milk energy output) on feed conversion efficiency. An "index of efficiency" is proposed which will enable cows which differ in milk yield, weight and breed to be ranked accordingly to their predicted "gross feed conversion efficiency".},
	issn = {1176-5283},
	author = {Glassey CB and McPherson JR}
}
@conference {39662,
	title = {The effect of herbage allowance on the dry matter intake and milk production of dairy cows},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {40},
	year = {1980},
	month = {Jan},
	pages = {59-63},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	issn = {1176-5283},
	author = {Glassey CB and Davey AWF and Holmes CW}
}
